An Optical Transport Network (OTN) is a core technology of a transport network. The OTN has abundant Operation, Administration and Maintenance (OAM) capabilities, a powerful Tandem Connection Monitoring (TCM) capability, and an out-of-band Forward Error Correction (FEC) capability, and can flexibly schedule and manage large-capacity services.
Four Optical channel Transport Units (OTU) having fixed line rates: an OTU1, an OTU2, an OTU3, and an OTU4 are defined in an OTN standard system. Levels of the line rates of the four OTUs are 2.5 G, 10 G, 40 G, and 100 G, respectively. A unit is bit/s, namely, bits per second. The four OTUs respectively correspond to four Optical channel Data Units (ODU) having same rate levels as those of the OTUs: an ODU1, an ODU2, an ODU3, and an ODU4. During signal multiplexing, an ODU of a rate level may be multiplexed to any ODU having a higher order than the ODU, to increase a data transmission rate. That the ODU1 is multiplexed to the ODU2 is used as an example. A payload area of the ODU2 may be divided into four tributary slots (TS), and each tributary slot is used to carry a piece of ODU1 data.
With the emergence of a large quantity of emerging services such as 5G mobile services (5th generation mobile networks), video services of, for example, 4K (4000 pixels) and 8K (8000 pixels), and Virtual Reality (VR), these services have diverse traffic demands and have a relatively high real-time requirement on bandwidth. An existing fixed tributary slot cannot effectively meet the requirement. Further, with extensive penetration of a Software-Defined Network (SDN), a customization demand of a customer and a demand for direct intervention to control a transport network continuously increase. The transport network needs to be more intelligently driven. This is not merely limited to programmability of a control plane. A data plane also needs to be assigned with programmability. The existing fixed tributary slot limits this capability and cannot meet a customized transmission requirement of a client service.